It's one of the few remaining issues that can bring Democrats and Republicans together -- fear of unchecked government drones.
Sen. Rand Paul's historic 13-hour filibuster has drawn renewed attention to a technological expansion that would have been unthinkable a decade ago, and new legislation that's meant to rein it in.
While the Obama administration increasingly employs armed drones as a pivotal counterterrorism tool overseas, domestic law enforcement agencies are also moving to broaden the use of surveillance mini-drones over the next several years. The Federal Aviation Administration projects as many as 10,000 licensed systems by 2017.
The lethal drones used in Pakistan are a far cry from the unarmed eyes in the sky used in America. But Sen. Rand Paul, R-Ky., and a host of other lawmakers see constitutional pitfalls across the board -- namely focusing on how armed, and unarmed, drones might someday be used against American citizens.
Paul and the senators from both sides of the aisle who joined him on the floor Wednesday described a bleak future where an unscrupulous government might use drones against its own population if left unchecked.
"Your notification is the buzz of propellers on the drone as it flies overhead in the seconds before you're killed. Is that what we really want from our government?" Paul asked.
Despite the filibuster, a vote on the nomination of John Brennan for CIA director -- whom Paul was technically holding up with his speech -- is expected to proceed as early as Thursday.
But lawmakers have already started pushing legislation to rein in the drone program -- legislation that might get a second look after Paul's dramatic performance Wednesday, and into early Thursday morning.
Rep. Zoe Lofgren, D-Calif., and Ted Poe, R-Texas, last month introduced a bill to regulate domestic drones much like the government regulates wiretaps.
It would require officials to obtain a warrant in order to perform many kinds of surveillance with those drones. Further, it would prohibit law enforcement drones from being equipped with firearms or explosives in U.S. airspace.
"As we enter this uncharted world of drone technology, Congress must be proactive and establish boundaries for drone use that safeguard the constitutional rights of Americans," Poe said in a statement last month.
The use of armed drones in U.S. airspace fueled Paul's lengthy filibuster Wednesday. Before he took the floor, Paul announced that he had received a letter from Attorney General Eric Holder which opened the door, in extremely rare circumstances, to using a drone to kill someone within U.S. territory. Holder said "catastrophic" attacks such as the Sept. 11 attacks or the attack on Pearl Harbor are examples of circumstances where the president could conceivably feel such an action is necessary.
Testifying on Capitol Hill on Wednesday, Holder agreed that it would be unconstitutional to use a drone on American soil against a U.S. citizen and suspected terrorist who did not pose an imminent threat.
Paul, during his filibuster, said he wanted a formal assurance from the administration that it would not use drones to kill noncombatant Americans.
Aside from the legislation in the House, members of the Senate Intelligence Committee have floated the idea of establishing a sort of drone court to screen potential targets -- much like a court screens surveillance of foreign targets in the U.S.
